End of the world
by ArtemisApollo97
Summary: Demigods are hunted endlessly, scientists of all sorts demanding their genetics. Demigods remain in hiding, but when the Earth is attacked by an unknown race, spreading mutagenic properties through simple injuries, will demigods be the only ones to help save the human race? Swearing and possible gore
1. The dangers of swimming

**I had this dream about the world ending, but I'm putting a twist on it. Demigods are known in the mortal world and are hunted ruthlessly for experiments in the genetics and mutagenetic departments. I do not own Percy Jackson, but Louisa is my OC. **

It was a fairly normal day, the sun shining outside and their P.E teacher forcing them to swim in almost freezing temperatures and at least a hundred metres. The pool was square and the tiles lining the bottom of it were brown. Most of the large, square room was brown, including the low ceiling.

A trio of girls sat to the side, trying to hide from their evil sports teacher, Ms Baker. Her limp, dull blonde hair was drawn back in a high bun. She had beady, blue eyes, thin lips and a hawk nose.

Strangely, there was a section near the girls that dropped down into the school's water supply. A back-up escape route should the need arise. It hadn't yet, but it was there, ready and waiting.

"Do you reckon he's down there?" Ellie sighed dreamily.

"Oh yeah, 'cos the school's dream boy hangs out in the sewers." Louisa rolled her eyes. Ellie's blue eyes hardened in annoyance.

"Just because you couldn't care less about boys doesn't mean you have to dash other people's hopes." She freed her long, thick mouse brown hair from its ponytail and fashioned it up in a loose bun. "And I asked him to meet me here." Louisa looked at her other friend, Molly.

Molly was shy, often hiding behind her dark hair and peering cautiously at people with her deep blue eyes.

Molly gave a timid smile and looked down.

"Molly, would you rather stay in a warm, clean classroom or go trekkin' around the sewers to find some desperate girl?" Ellie scowled at Louisa. Molly's smile broadened slightly.

"I'd prefer the classroom." She said quietly. Louisa nodded in agreement.

"Louisa!" Louisa groaned. Their teacher had taken a liking to Louisa as she was a natural strong swimmer and skilled diver. Every so often, Ms Baker would grant Louisa a break from swimming, which resulted in Louisa worming her friends out of the sport too.

Louisa loved swimming. But her teacher took it too seriously. Louisa may have been competitive, but she saw swimming as a form of entertainment. She did not want to end up like her teacher.

Ms Baker called her again. Louisa sighed.

"Teacher's pet." Ellie teased. Louisa smirked and Ellie looked worried. She had every right to be worried as Louisa wasn't one to annoy. If you upset or angered her, she would happily get her own back.

Louisa got up and stood at the end of the pool, in a line with a few other girls in her class. None of them looked happy. None of them could get from one end of the pool to the other without stopping occasionally. Louisa could do that and back without stopping.

While Louisa swam, Ellie glanced back into the water supply. Water tumbled out of sight beneath them and gurgled busily. Louisa had a point about the school's dream boy remaining in a classroom instead of walking through the water that churned and flowed so fast, it could easily knock anyone off their feet.

Ellie pulled her gaze away. She and Molly watched their friend reach the other end of the pool shortly before the others. Louisa twisted underwater and kicked off the wall. Most of the other girls had to stop and turn, not entirely keen on going underwater. Ellie was like them. She would change into her swimsuit, but would do as little swimming as possible. It was tiring and the water was freezing. How Louisa managed to swim perfectly well in that climate, she wasn't sure. Louisa was someone who took anything life threw at her. If life gave her lemons, she would make super lemons.

Molly tapped Ellie's shoulder and pointed.

Ellie frowned. Behind Louisa, something had broken the surface.

A fin.

It was a dull orange-brown colour, jagged and fairly limp. It was nearly as long as Ellie's arm.

"Miss!" Ellie shouted. The teacher looked round, her usual scowl in place. "Something's behind Louisa!" The teacher looked, but the fin had disappeared. All that could be seen was a dirty peach coloured blob, distorted by the water and following Louisa.

Louisa suddenly dived and the blob followed. The teacher shouted at the students to get out of the pool, which they did all too gladly.

The pool was twelve feet deep. Louisa was known to reach the bottom and stay there the longest out of all the girls. Once it had been ten minutes, in which the teacher had dived in to make sure Louisa hadn't drowned. Louisa, however, had been fine and had waved cheekily at their teacher.

Louisa clambered out of the water as it exploded behind her. Screams went up, but Louisa remained calm, a fire burning in her eyes.

The dirty peach blob had surfaced. Whatever it was, it was hideous. It had a long snout, with huge, jagged pincers in its mouth, dripping with water worryingly tinged green. It's large, bulging grey eyes were oddly bird-like, studying everything with a three-sixty turnaround. It was at least ten feet long and seemed to have eaten two small cars for breakfast. It had a tail like a whale's, but a fin along the end, similar to the one on its back.

The thing pulled itself up onto the side, showing it had frog limbs and webbed feet attached with long, curled, dangerously and frighteningly sharp claws as dark as obsidian.

The abomination's terrifying eyes shifted and focused on Louisa. Louisa met the gaze with a defiant glare, one she reserved for bullies.

Louisa took shit from no-one. And that clearly extended to hideous beasts as well.


	2. Cold fingers of death

The monster opened its jaws, pincers snapping and dripping venom. The smell of rotting meat was unleashed and everyone tried not to breathe through their noses.

It tried to launch itself at Louisa, but was stuck. Louisa had her trademark, triumphant smirk on as the monster struggled to free itself from the water tangling around its body.

Everyone backed up further. Louisa noticed, looking round in time to see Ellie and Molly moving away. A flicker of pain scratched through her eyes before she shrugged it off and looked back at the beast.

Ellie and Molly could not believe it.

Louisa was a demigod.

They had known each other for near enough ten years, yet Louisa had never said anything about her uniqueness. Louisa had always been different, ADHD and dyslexic- and highly stubborn. She had the potential to be popular, to stand in the _in _crowd, but she stood up to bullies who picked on the little kids. This didn't win her many favours with the bullies and had landed her in many fights. But she didn't care. She just strolled through life like a walk in the park.

But for her to be a demigod…

It was out of the question. Unheard, unspoken and unthought-of.

The water gathered in a thick column, raising the beast high out of the water. It writhed and shrieked in protest, the high pitched wails damning eardrums and shattering glass. Girls started to run for the exit, the P.E teacher forgetting the rule of no running by the pool.

The only ones that remained were Louisa and her two friends. The teacher was long gone.

"So when were you going to tell us?" Ellie snapped.

"After I've dealt with this thing." Louisa replied calmly.

"Did it not occur to you to drop a hint at some point over the last ten years? _Hey guys, what's up? Do you like hotdogs? Red's my favourite colour. Oh, might be nice to mention that I'm a demigod._"

Louisa had the nerve to laugh. "It's not funny!" Ellie exclaimed.

"I'm laughin'. I'm findin' it funny."

"We should go, Ellie. They'd have sensed her by now." Molly had a point. Technology had developed so much and there was a wide range of demigod-detecting and demigod-restraining mechanical devices.

Ellie's father and older brothers were demigod hunters.

Louisa watched them leave, a pang of hurt and treachery flowing through her like ice water. In a few seconds, anger replaced those feelings and adrenalin surged through her.

"This is your fault, bitch." She told the monster. "Ya had ta come along 'n' make ma two friends go. Oh, I'm also gonna get busted by idiots in white coats. Thanks." The water spread along the beast, covering it with a layer of water as thick as Louisa was tall. The water expanded slightly as it froze. The abomination became immobile inside, eyes wide in panic, mouth agape in silent wails. An eerie silence settled down around her, broken by the gurgling of water from the water main.

Louisa raised her hand and clenched her fist. The ice cracked and bucked under the pressure, distorting and twisting the creature's body.

She pulled her hands apart and the ice copied, stretching the beast and creating tears in its scaly skin. Then she clapped and the monster was suddenly in a trash compactor, bunching up, ice cracking and creating points that buried themselves in its flesh. Louisa heard the sound of bones crunching and breaking, spotting the unnatural arc of the thing's spine and the painful looking bends in its limbs and tail. Its head had twisted to one side at an impossible angle.

Louisa snapped her fingers and the ice exploded.

As did the beast.

Gobbets of flesh, bone, blood and internal organs rained down, splattering the bottom of the pool in red, white and pink.

Louisa allowed the ice to return to its watery form before she heard the tell-tale whirr of helicopters. She sighed. "Cold metal lab table, here I come."

Little did she know, she was never to meet the cold metal lab table.

Instead, she was to meet something- and someone- much better.

And that was before things went from bad… to worse…


	3. Helicopter

The helicopter landed. Louisa hadn't seen the point in running from it. Instead she had sat on the slope that ran down from the patio outside the swimming pool block.

She hadn't expected a fairly scrawny kid in a bright orange T-shirt with curly hair and elfish features to grin at her from the helicopter's controls. He landed the helicopter and the side door slid open.

Louisa nearly had a heart attack.

A boy about her age was having the same reaction.

Both of them had thick, raven hair and bright, sea green eyes, tanned skin and athletic builds.

"What's taking so long, Seaweed Brain?" A girl with curly, blonde hair like a princess's and stormy grey eyes pushed the boy out of the helicopter. The elf boy at the helicopter's controls laughed.

"That was harsh, Annabeth." The elf boy laughed.

"Someone had to do it." The blonde girl and the elf boy jumped down as the boy version of Louisa got to his feet, dusting himself down.

The blonde girl looked at Louisa and her eyes widened. "Right," She looked back at the boy she had pushed. "Sorry about that."

"For a daughter of Athena that wasn't very smart." Louisa got to her feet slowly. The elf boy noticed.

"You are a demigod right?" He asked. Louisa nodded slowly. The boy grinned from ear to ear and clapped excitedly. "We'll get along just great. Come on." He and his two friends, all in bright orange T-shirts clambered back onto the helicopter. Louisa didn't go with them.

The boy that looked like her stopped and looked back.

"It's either you come with fellow demigods or the hunters will come and get you."

"Hunters…" Louisa repeated quietly. Cold metal table or demigod… gang thing?

Demigod gang thing.

Louisa ran forward and jumped abroad. The elf boy beamed at her as Louisa's male counterpart pulled the door closed. "He can fly this right?"

"He's a son of Hephaestus. He knows what he's doing, right Leo?" Leo's hands were flying over the control as they took off. "Leo?"

"Huh?" Leo looked round, clearly having been dragged out of his own world. "Oh right, yeah." He smiled broadly and bowed formally to Louisa. "You're in the safe hands of Leo Valdez, ma'am."

"Leo…" The blonde girl warned.

"I know, I know, man the controls." Leo turned back to the controls and started humming the Power Ranger theme song. "Don't mind him; he's seriously ADHD, even for a demigod."

"Are all demigods ADHD then?"

"It help keeps you alive in battle."

"OK." Louisa looked at all of them. "Who are you people?"

"Well, you've already got Leo's approval-" Leo turned.

"That's a high honour!" He grinned.

"Controls, Valdez!" The blonde girl snapped, but Louisa could tell she was trying not to smile. "I'm Annabeth Chase, daughter of Athena." Annabeth held her hand out. Louisa shook it.

The boy that looked like Louisa held his hand out too.

"Percy Jackson." He said, Louisa shaking his hand. "Son of Poseidon."

"That's pretty neat." Louisa grinned. Percy relaxed slightly and returned the smile, but there was still a gleam of unease in his eyes. "What's the matter?" Louisa asked, dropping his hand. Percy didn't answer her, looking into her eyes as if searching for answers.

"It's 'cos you look freakishly alike." Leo piped up. Annabeth glared at him. Leo didn't even need to turn around to know Annabeth was glowering at him. "Sorry." He mumbled.

"Well, it ain't my fault."

"Louisa, what happened in the swimming pool?" Annabeth asked.

"Big monster thing."

"What happened exactly?" Louisa sighed and explained. They were all good listeners.

When Louisa mentioned controlling the water and turning it into ice before forcing the ice and monster to explode, Annabeth and Percy shared a look. "What?"

"Uh, that." Annabeth pointed up, her features suddenly bathed in a green glow. The whole helicopter was bathed in the glow.

Louisa looked up and saw the hologram of a trident floating above her head. She was still staring up at it after it had faded.

"So… I have a sister?" For some reason, Percy sounded hurt. And for some reason, this annoyed Louisa. She glared at him. Percy was surprised at first, but glared back.

Annabeth stepped between them.

"Percy, I know what you're thinking. Just… let me do something first." Annabeth looked at Louisa. "When's your birthday?"

"August 18th." Percy scowled. Annabeth ignored him.

"When were you born?"

"Nineteen ninety three." Percy's scowl deepened. Annabeth looked at him. "What's his problem?"

"You need to talk to your mom." Annabeth told him, ignoring Louisa.

Louisa didn't like being ignored, but they hit some turbulence and she ended up staggering back until she stood next to Leo. He grinned at her, clearly unaware of what was going on behind her.

"How'd ya know how ta fly this thing?"

"It's a son of Hephaestus thing." Leo noticed Louisa's confused expression and quickly explained a few children of Hephaestus skills. "I can also control fire, which is a rare thing amongst us Hephaestians."

"Hephaestians?"

"My name for the Hephaestus kids."

"Why's it so rare?"

"It's dangerous. The last Hephaestian to control fire, um, I think they did the fire of London, can't remember…"

"Right." Louisa said uncertainly. They hit another spot of turbulence. Leo quickly grabbed her hand and stopped her from tumbling over.

When the turbulence had passed, Leo hadn't let go of her hand. "Uh, fire boy?" He looked back round from wrestling with the helicopter's controls and realised he still had hold of her hand. His cheeks went pink and he quickly let go.

"Thank the gods Piper's not here…" He mumbled.

"Who's Piper?" Leo didn't answer, humming the Power Ranger theme song again, but this time with a hint of nervousness.

Louisa returned to Percy and Annabeth, who had wisely sat down and strapped themselves in. Louisa did likewise. "Right, what's goin' on?"

"Well, we've decided to talk to Percy's mom when we get to the safe zone."

"Safe zone?" Annabeth nodded, but didn't elaborate further. "How long will that take?"

"Well, if we're lucky, half an hour. But we're demigods and are obviously not lucky and have a military helicopter on our tail." Leo said, looking round for orders. "This one doesn't have any weapons, guys. It just flies."

"What kind of chopper doesn't have weapons?"

"The one we picked hurriedly." Leo replied, smiling sheepishly.

"Fair point." Annabeth sighed, slouching in her seat. Louisa noticed Annabeth's eyes dart from the son of Poseidon next to her to Louisa and back again. After a few seconds this annoyed Louisa.

"What?" She demanded.

"Don't take it personally, but it Percy's and your fault that we were found so quickly." Percy didn't seem as annoyed as Louisa. Before Louisa could protest, Annabeth explained. "You're children of Poseidon- a Big Three god. They're not supposed to have children. You're too dangerous, too powerful and attract a lot of attention. It used to be monster attention, but now its hunter attention."

"Hunters, as in demigod hunters, right?" Annabeth nodded. "Just checkin'."

The sound of bullets peppering the helicopter's hull made them jump.

"Leo!"

"I'm trying! There's not a lot I can do though!" Louisa unbuckled her straps and jumped to her feet.

"Turn it around!" She ordered. Leo paled.

"We'll be dead in seconds!"

"Just turn it round!"

"But-" Leo protested. Then he shook his head. "I'm not turning it around. We'll all be dead."

"Fine, I'll do it myself." Louisa pushed Leo out of the way with such force he fell over onto his backside. Louisa had figured out which one was the control stick after watching Leo fly the helicopter. It was nothing turning the helicopter around.

Leo leapt up and wrestled her for the controls.

"We'll all get shot! I'm not gonna let you do that!"

"I can get rid of them!"

"Do it without turning us round then!"

"I have ta see them!"

"I'm not risking everyone 'cos of you!" Someone grabbed Louisa from behind and pulled her away. Leo set the helicopter back on the straight and narrow path as more bullets thudded against the hull.

"Let me go!" Louisa shouted, squirming and fighting her new brother.

"Think about someone else before you do anything!" Percy retorted, tightening his hold on her. Louisa kicked backwards and accidently caught him where it would hurt most. Instantly, Percy dropped her and doubled over, groaning in pain.

Louisa had forgotten about Annabeth. The daughter of Athena stood between Louisa and Leo.

"Move it blondie!" Annabeth's eyes flared in anger and she drew her knife.

"Do not. Call me. Blondie."

"Very sorry. Blondie. Now move before those idiots hit an engine or somethin'." Leo looked round. Judging by the startled look in his eyes, he hadn't thought of that. It was either carry on flying and get shot out of the sky or turn the helicopter round, follow through with Louisa's plan (whatever it was) at the risk of being shot.

Annabeth glared at her, going through their predicament in her mind at the rate of a hundred miles an hour.

Percy groaned, rolling onto his front and pushing himself up.

Louisa couldn't believe that a supposed daughter of Athena was taking so long to come up with an answer. At this rate, they'd be falling out of the sky in no time.

**Long chapter for you lot. Count yourselves lucky, I made this up on the spot with two chocolates and a bag of crisps. **


	4. Water can kill

**Sorry I haven't updated on this in ages. I only had inspiration for future chapters, but I'm going to try something. Sorry if it's drabble.**

* * *

Leo reluctantly turned the helicopter around. Louisa caught the eye of the opposing pilot and held his gaze stubbornly. A few seconds passed in tense and probable danger, but the pilot suddenly choked up a waterfall of water and slumped over the controls, contorting and thrashing about. The control pilot was trying to steady the helicopter and help his colleague, but it wasn't long before he was clutching his head and screaming in agony. He toppled back in his chair and blood splattered the window screen in a violent splash of scarlet.

"All done." Louisa said calmly, "Ya can carry on flyin' now." She told Leo, walking off, sitting in her seat and strapping in. Leo automatically turned the helicopter around and flew away, sickness settling into his stomach. Percy and Annabeth sat opposite Louisa and just stared at her. Louisa remained unfazed.

"You killed someone."

"OK."

"That doesn't bother you?" Annabeth frowned.

"It's either we kill them or they'll kill us." Louisa said simply.

"What did you do to them?" Percy asked.

"A human body contains seventy-eight percent water." She smirked. She let the rest hang in the air. Annabeth paled, Percy looked sickly and Leo started humming the Power Rangers theme song again. "How long until we get ta this safe zone thing then?"

"T-twenty minutes." Leo stammered. Louisa nodded.

The journey was carried out in silence.


	5. Camp Half Blood

Camp Half-Blood.

That's what it was called.

Louisa looked around, taking in the hundreds of cabins, the climbing walls, the basketball courts and everything else.

"Percy, Annabeth, Leo. Welcome back."

"Hey Chiron." Annabeth grinned. Chiron the centaur looked at Louisa. She kept her expression neutral. Chiron looked curious.

"Hello. What's your name?"

"Louisa."

"As you may already know, I'm Chiron." He looked at Percy and Annabeth. "Has she been claimed?"

"Yeah." Percy muttered, throwing a dark look in Louisa's direction. Louisa instantly glared back, balling her fists. Chiron looked between the two before understanding.

"Well, we were all wondering when you would show up again."

"Huh?" Louisa and Percy said together. They glared at each other again.

"Percy, you mother told me she was expecting twins, following Poseidon's instructions; she did not tell me of your heritage then. She was looking for advice on what to do as Poseidon had advised to separate the two of you."

"So, I got ditched 'n' Mr Sunshine here was kept?" Percy scowled at her.

"Well, you would have caused the most trouble." Louisa grinned.

"Sweet."

"Have you heard the news?" Chiron asked, suddenly serious.

"What news?"

"Mortal children aged three to ten years old are disappearing throughout the city and its surrounding areas."

"What about demigod children?" Annabeth asked, thinking of her five year old half-sister, Carly. Carly was a miniature version of Annabeth and she continuously looked up to her. Annabeth was Carly's sole carer. If something had happened to Carly…

Annabeth didn't want to think about it.

"All demigods in both camps have been reported safe. Updates are passed up every hour. Satyrs have been sent out to track down as many demigods as possible of all ages."

"How and why are children disappearing?" Leo asked.

"Strange appearances have been reported - some things that will greatly spark your interest, Mr. Valdez." Leo perked up in curiosity. "Strange flying ships." Chiron glanced up and frowned. "Like that one there."

Everyone looked up.

It was typically UFO shaped, but was entirely camouflaged with the blue sky and clouds above. Flashing lights and occasional glitches ruined the ship's attempts at being discreet.

"I want one." Leo grinned, his eyes shining. Louisa rolled her eyes, her arms folded.

"Apparently, there are hundreds of those things, all of various sizes above the city and surrounding areas. They are also dispatching the most hideous of creatures. Mortals have been warned to stay indoors."

"If everyone's indoors, how come all the kids are bein' kidnapped?" Louisa frowned.

"Not kidnapped directly, Louisa. One second they are there and the next they are gone."

"So, they're bein' zapped away or somethin'?"

"You could put it like that, yes."

"What can we do?" Percy asked. Instantly, Louisa's bristled and rounded on him. Percy met her glare defiantly.

"Are you _nuts_? Humans will happily kill us 'n' you wanna help 'em?" Percy clenched his jaw stubbornly and they all saw the anger flare with power in his sea green eyes.

"It's the children I'm worried about." He clenched his fists. "Besides, helping them might show them that we're not that bad."

"Helpin' 'em will make 'em think," Louisa switched to a false and enthusiastic tone, "_Oh yay! Hundreds of demigods to capture, torture, kill 'n' experiment on_!" Louisa finished in a growl.

The started squaring up to each other, but Annabeth had the sense to step between them.

"You both have a point. But we have to help. Those poor kids… not to mention their families. If we don't try to make things better, they can get so much worse."

The Poseidon siblings continued to glower at each other, but thankfully they remained silent.

Annabeth thought quickly. "Alright, we need to send out scouts to the city and organise search parties to learn about and find those lost children."

"Annabeth, thousands and thousands of children are missing. Gods know where they are or if we find any of them."

"Percy, we have to have hope and we have to help." Annabeth ran a hand through her hair.

"How can ya have a smart blonde?" Louisa said without thinking. Annabeth's eyes instantly flashed in anger.

"My mom is Athena. Smartest of all the gods."

"Technically, she's the wisest, but hey." Louisa shrugged. "Whatever floats ya boat."

"We should get those scouts and search parties organised, Annabeth." Percy said, putting a warm, yet restraining arm around her. The two walked off, having a hushed discussion.

"I must check on the campers and speak with Mr. D." Chiron told them. "Try to keep the peace, please Louisa."

"I can try, but I can't guarantee nothin'." Chiron just nodded, as if he had been expecting that response. He trotted away.

"That leaves you and me!" Leo beamed.

"Great." Louisa sighed. Leo remained unfazed.

"Little bit more enthusiasm next time, alright chica?" Louisa frowned.

"Chica?" Leo looked busted but he kept his grin in place.

"I call all the girls 'chica'. I'm such a ladies man." He ran a hand through his hair and smirked.

"Yeah, I can tell."

"Hey, less sarcasm!" Leo playfully and lightly smacked her arm. Louisa smiled. "I should give you tour before all the world destruction starts."

"Why would I need a tour? It ain't like I'm stayin'."

"You have not truly lived until you have seen all of Camp Half-Blood while eating my tofu burgers."

"Right…" Louisa said, not sure if he was reacting to the ADHD being a demigod bought or he actually had something wrong with him.


	6. Valdez tour of CHB

Leo knew how to give a tour and how to make tofu burgers.

"And this is your cabin." Leo grinned, spreading his hands with a flourish. Louisa looked at the Poseidon cabin. It was very unlike the other cabins and it gave her a sense of home, even though she hadn't even stepped inside. "What'd you think?"

"It's pretty cool." She looked at him. "Ya ain't shown me your cabin." Leo smacked his forehead.

"Duh! Forgot the most epic cabin of all time!" He summoned a flashlight from his tool belt. The strange ship's shadow had settled over them. The thing was moving incredibly slowly, but thankfully no demigod children had been taken.

Leo switched the flashlight on, a circle of blue light falling on the ground. "This way, ma'am." He said formally and started walking. Louisa could only follow.

Leo grew increasingly excited as they neared his cabin. He ended up breaking into a run. Louisa followed at the same pace, not keen on getting lost.

Leo bounded up the steps to the Hephaestus cabin, spun on his heel and threw his arms out, grinning broadly and cheekily. "Ta-da!" He exclaimed.

"Nice." Louisa nodded, taking in the smoke stacks on the roof and the crates of scrap metal.

"You haven't seen the inside yet." Leo jumped the steps, bounded forward and grabbed her by the wrist.

Entering the Hephaestus cabin, Louisa was surprised to see it empty of people.

That's when Leo took her down into the underground forge.

Leo's siblings were very different from Leo. He was kind of scrawny and hyperactive whereas they were burly and well-built, even the girls, and they seemed highly serious, but they did smile when Leo bounced past.

"Who's your friend, Leo?"

"Percy's long lost twin sister." A hush settled down over the Hephaestus children. The only sound was the popping and crackling of a fire in the back.

Louisa looked at Leo's half-sister who had asked who she was.

Leo looked round at his half-siblings. "Don't even try to contain your excitement, guys." A few laughs went up and many more smiles were offered. The tension eased up. "Have you heard what's going on topside? There's this mega cool ship- ours was way better- but still, I want one."

"Ship? What ship? Leo, we don't know what's going on up there, remember? We've been down here all day. Remember the blue prints we showed you this morning?" Leo scrunched his face up in a cute, thoughtful way.

"Was this during my 'I-need-coffee-haze'?" He asked.

"Probably." Leo smiled again.

"Enlighten me, dear sister."

While Leo offered his ideas for his siblings' group project- "You really need a coffee machine and Greek fire flamethrowers." – Louisa looked at various projects, finished and unfinished. She saw something that looked like an hour glass with wires sticking out of it. Louisa went to pick it up, but someone else snatched it up.

Leo grinned at her. "You don't want to touch this, Lou."

"Why?"

"It zaps anyone who isn't me."

"Oh. You made it then?" Leo nodded, smiling and studying his project. "Why does it zap people?"

"Well, it was meant to help protect the camp and zap away people and monsters we don't want here. But it only seems to like me, as it rightfully should. I can't fix it, but I will someday."

"Cool." Leo grinned at her and set the hour glass back down.

"We should see how those scouts and search parties are doing."

"Did ya talk to those guys about what's goin' on?" Louisa nodded in the direction of his siblings, who were all clustered around the big project table in the middle, the blueprints spread out on the table top.

"What do you think I am? Stupid?"

"A bit." Louisa admitted. Leo looked surprised before shrugging it off.

"What they're building is like my failure of an hourglass, except their one will probably work."

"What if it zaps somethin' friendly?"

"Well, they'd be a pile of smoking ashes. A loss, but it'll improve our work." Louisa regarded him carefully. Leo grinned. "Just kidding. It shouldn't do that to friendlies, but still…"

"I'll take ya word for it."

"Are you sure that's safe?"

"Nothin' I do is safe." Leo grinned.

"Fair point."


	7. Found one, a gazillion more to go

Louisa and Leo walked into the Athena cabin. All the Athenian kids were clustered around five tables pushed together in the centre of the room. The table tops were scattered with paper, pens, books and IPads. Annabeth stood with a five year old girl balanced on her hip while they all listened to one of her half-brothers voicing his opinion on what to do with the scouts and search parties.

Percy stood to one side with two others. A girl with short, black hair that was spiked up stood to his left. She had electric blue eyes and wore ripped, punk clothes and combat boots. She had a silver bow and a matching quiver of silver arrows slung across her back. The other was a pale boy with shaggy dark hair and deep brown eyes. He wore dark skinny jeans, scuffed army boots and a black hooded jacket, his hands deep in his pockets.

The punk rock girl turned and saw Louisa and Leo. She smiled warmly.

"So you're the new cousin." She moved over and shook hands with Louisa. "Thalia Grace, daughter of Zeus and Hunter of Artemis."

"Louisa. Uh, daughter of Nep- Poseidon." Thalia looked at her curiously. "OK, I nearly said Neptune 'n' I ain't got a clue why."

"You might be like my brother. He's a Roman demigod and Neptune is Poseidon's Roman form."

"Oh. OK."

The pale boy and Percy appeared either side of Thalia.

The pale boy regarded Louisa for a few seconds, but he didn't speak.

Thalia spoke up for him.

"This is Nico, son of Hades. He doesn't speak much until you get to know him properly." Louisa said 'hi' anyway. Nico just nodded.

"Lou?" Louisa turned. Annabeth waved her over. "You know the grounds around and under your old school?" Louisa nodded. "Can you help us map that so we can send out a scout party?"

"Sure." Louisa was handed a nicely sharp pencil and was directed to her old school on the map.

Annabeth moved over to the other Big Three children, Carly on her hip.

"Can you get Ares kids, Hecate's kids and the archers from the Apollo cabin and lead them around the border? See if you can find anyway weaknesses."

"Okey dokey." Thalia grinned. Annabeth shot Percy a 'be careful' look as Thalia grabbed her cousins by their upper arms and dragged them outside. "So, Percy, what'd you think of your new sis?" Percy shrugged, looking at the ground. Thalia and Nico shared a look, a rare smile gracing Nico's lips.

"Percy, you've got that look. What's the matter, mate?" Nico asked.

"Mom and Dad never told me I had a twin." Percy sounded a wee bit pissed off, but he tried to remain calm.

"Uh… health and safety." Thalia suggested. Percy's sea green eyes pierced hers, unimpressed. Thalia pursed her lips stubbornly. "Don't give me that look, Jackson, or I'll call lightning down and fry your ass."

"Cool." Percy said, nodding. "The world makes sense again." Thalia punched him in the arm.

"Last warning, Kelp head."

"Sure thing Pinecone face." Nico pushed in between the two cousins before they could see which was better- archery set or a sword.

"We're all gonna be nice and shut up now, aren't we?" He said, his eyes glittering. Percy and Thalia remembered his creepy, zombie calling powers and nodded meekly. "Good children."

* * *

After mapping her old school's grounds and sewage systems, (which she only knew because she had sensed the running water under her feet at school), Louisa ventured out, Leo with her. He seemed keen on following her like a lost-puppy.

Louisa saw her brother and cousins step up onto the porch of the Ares cabin. She carried on walking in the opposite direction, only half-listening to Leo spewing random facts about the gods and things that he thought were strange- "Why is the sky blue?"- But she was mainly focused on the horrible, burning sensation that speared over her tanned skin.

This only happened when shit was going down nearby.

"Uh, Lou, it's not safe to go- and she's gone." Leo passed the safety of magical barrier of Camp Half-Blood, feeling as if he had been thrown into a shopping mall on Christmas Eve in nothing but his boxers. He glanced to the west and saw the sun was an hour from fully set. "Lou, what are you doing?"

"Ssh!"

"But-"

"Ssh!" Louisa stopped at the base of the hill. Leo did too, a step behind her. On the other side of the road were dense bushes and a wide range of trees. Louisa was staring into the murky darkness under the treetops.

Leo elbowed her lightly, offering a quizzical look. Louisa pointed.

As if on cue, a young child burst out of the bushes. He sprinted across the empty road as one of the strangest creatures Leo had even seen lumbered out from the trees.

The boy hid behind Leo's legs, but he barely noticed, staring at the creature and unaware of a sword appearing in Louisa's hand.

The creature was humanoid in size and shape, but was an exact replica of the monstrosity Louisa had killed in the school swimming pool.

Running down its back, along its spine was a dull orange-brown jagged fin. It toes and fingers were webbed and it had gills in the sides of its neck, but somehow it was breathing fine. Its skin was a dirty peach colour and mildly scaly. It had the teeth similar to a shark's and was now snarling at them as it blundered across the road, its miniature whale tail dragging on the floor as it ran. It shrieked, making them all cover their ears. Their minds rang in pain and their vision became blurred. The only thing they could see clearly was the creature's scarlet eyes dancing about as it ran with slight imbalance and a limp.

The boy was crying, hugging Leo's leg. Leo wanted to look down at the boy, but was too scared to take his eyes off the monster in front of him. He only noticed Louisa moving forward to battle this abomination when she was a metre in front of it, her bronze-gold sword at the ready.

The beast howled at her and picked up the pace, tripping slightly on its webbed feet. Louisa took advantage of that and sliced downwards. A spurt of green blood splattered her and the road. The thing's head plopped on the tarmac and the body fell backwards. The boy cried in fear and disgust.

"Lou… sword… _head_?" Leo didn't know what to make of it. It wasn't every day a newbie decapitated a strange mutant alien monster thing. "Lou!" She just smirked at him, the green blood eerily of similar colour to her eyes. Leo swallowed nervously before turning and kneeling to talk to the boy.

He had sandy blonde hair and terrified, tearful hazel brown eyes. His face and neck were covered in minor nicks and scratches and his clothes were muddy. He wore blue, denim dungarees with a yellow and orange striped, long sleeved T-shirt on underneath. He wore muddy, scuffed trainers that had once been white.

Leo gently brushed dried mud from the boy's forehead. "What's your name?"

"C-Clint."

"Like Clint Eastwood?" The boy frowned in confusion. "He's some cowboy dude."

"Batman's better." The boy said meekly. "Who are you?" He asked, his fingers closing around Leo's thumbs.

"I'm Leo and Little Miss Executioner over there is Louisa." Clint looked at Louisa cautiously. Leo looked at her too. "Lou, put your sword away, you're scaring him." Louisa sighed and her sword shrank back into a red and gold watch. "Neat." Leo grinned. He looked back at Clint who was staring open-mouthed at the watch.

"Th- that- that's magic!" He cried. Leo nodded in agreement. Clint's brown eyes locked with his. "Do you have magic that can get me back to my daddy?"

"Who's your daddy?"

"Mark."

"What's his last name?"

"Um…"

"What's your last name?"

"I'm Clint Rose."

"Mark Rose." Leo looked over his shoulder at Louisa. She just shrugged. Leo turned back to Clint. "Here's what we're gonna do. We're going to take you somewhere safe and you can stay until we find your daddy. Does that sound good?" Clint looked ready to cry again, but he nodded. Leo stood, picking Clint up and balancing him on his hip. "Have you ever been to a summer camp, Clint?" Clint shook his head as Leo and Louisa started back up the hill. "Well, you'll like this one. Everyone here has some sort of magic power and weapon. And, get this," Leo paused for emphasis, "I can make amazing tofu burgers."

"What are tofu burgers?" Clint asked nervously. Leo stopped dead in his tracks, staring at Clint disbelievingly. Clint giggled, his nervousness still fairly strong.

"How can you not know what a tofu burger is?" Clint shrugged. "That is it. I will feed you tofu burgers until you explode." Leo tickled Clint's stomach, making the youngster squirm and laugh.

"Leo, if he's mortal, he ain't gonna get inta Camp, right?"

"Hey, hey," Leo half-turned to look at her, "Do _not _doubt the supremacy and high intelligence of Captain-Leo-of-the-Argo-Two-Valdez, sister." Louisa did not look impressed. "Fine. Be like that." And Leo turned and carried on walking.


	8. Piper

"Who's this?"

"You're horse man."

"Centaur, my dear boy. What's your name?"

"Clint Rose." Leo replied as Clint hid his face in Leo's shoulder.

"Nice to meet you, Clint." Chiron looked at Leo and Louisa. "Louisa, what is that on your face?"

"Blood."

"But… it's green."

"Yep."

"What has happened?" Leo and Louisa explained. Chiron remained in a stunned silence before telling Louisa to go and clean up the blood. "Well, Mr. Valdez, you could take young Clint here to the Hermes cabin or find someone else to look after him."

"Can't I look after him?"

"The Hephaestus cabin's forge isn't exactly safe for him. Too many people."

"Bunker 9 will be fine then." Leo bounced Clint in his arms, gaining the boy's attention. "How'd you feel about making your own toy plane?"

"Can we make a Batmobile?"

"Shoot, why not?" Leo grinned. Chiron watched him go; pondering the thought of Leo making a good father should the time come.

* * *

"What happened to you?" Louisa looked round, trying to get a patch of dried green blood off her forehead. Her new brother stood in the doorway, arms folded. Louisa turned back to the bowl of warm water, dampening the cloth. "Don't answer then." Percy grumbled. Louisa heard him move into the cabin's bathroom.

"Fine by me." She muttered, finally removing the dried blood.

"So, this is where you're hiding." Louisa looked round. Annabeth smiled at her. "I've been looking for you for ages."

"What's up?"

"You're part of the scout group to your old school."

"Cool."

"Where's Percy?"

"Sulkin' in the shower."

"Thanks." Annabeth moved to the bathroom door and knocked. "Seaweed Brain?"

"What's up, Wise-girl?"

Louisa saw some lovey-dovey mush on the way and took her leave. She went to the Hephaestus cabin, noticing that half of the ship above had passed over the camp.

Leo wasn't in the cabin nor was he in the underground forge. One of his siblings suggested he was in Bunker 9. Louisa had no idea where that was, but she set out anyway.

She walked past a pink cabin that smelt strongly of roses and perfume. Louisa barely noticed the figure dart down the stairs until they slammed into her.

"Sorry! Sorry!" Whoever had apologized pulled Louisa to her feet. "Are you OK?"

"Couple of bruises, but I'm good. Did ya not see me or somethin'?"

"Sorry." The girl smiled sheepishly. She was Louisa's age and height with layered hair and multi-coloured eyes. "I'm Piper." Piper held her hand out.

"Louisa."

"You're Percy's new sis, aren't you?"

"Yeah. He don't seem too happy 'bout it though."

"Percy's a strange guy sometimes. I think only Annabeth understands him." Louisa looked at the pink cabin behind Piper.

"Ya mom's Aphrodite, right?" Piper nodded. "Cool. Uh, do you have any idea where Bunker 9 is?"

"Looking for Leo?" Louisa nodded. Piper looked at the sun, now a thin arch above the horizon. "If we hurry, we can get there before sundown. The woods aren't exactly nice in the dark."

"Yeah, OK. Why'd ya barrel inta me then? Someone givin' ya trouble?"

"No, well, kinda, but it's not anything I can't handle. My little sister wanted to give me a makeover but she's still getting the hang of make-up and stuff and I didn't really want to look like a clown."

"How'd old is ya sis?"

"Six, bless her."

"Right. Midget kid then?"

"Midget kid?" Louisa just nodded.

"Bunker 9."

"Oh yeah. This way!" Piper grinned.

* * *

They reached Bunker 9 just as the sun disappeared behind the horizon.

"Leo!" Piper called.

"Pipes?"

"Leo, I told you not to call me that!" Piper sighed. "Where are you?"

"Hiding." Leo called back.

"Oh for gods' sake…" Piper mumbled.

"Leo, this looks breakable!" Louisa called out, picking up a nearby and half-finished invention. "Looks important too!"

"Alright, alright! Don't break anything!" Leo appeared a minute later, Clint at his heels.

"Oooh, who's this little cutie?" Piper moved forward and knelt to greet Clint. Clint blushed and hid behind Leo's legs.

"That's Clint." Leo grinned. "He likes Batman."

"I can tell." Clint held a Batmobile toy. "Did you make that for him?"

"Yeah."

"It's really cool." Clint mumbled. "Drives on its own."

"Leo's clever like that, isn't he?" Clint looked up at Leo, who smirked and nodded.

"Leo's supreme commander of the Argo Two and the ladies love him." Piper gave a disbelieving laugh, smacking Leo in the shin.

"Ow!" Leo nudged her with his foot, making her lose her balance. "Watch it, beauty queen, or face the wrath of Fire King."

"Repair boy."

"Fire King."

"Repair boy."

"Shut up." Louisa suddenly said. Piper got up and dusted herself down. "Right, ya arguin' like midgets, like him." She waved a hand at Clint. "In case ya ain't noticed, kids are disappearin' left, right 'n' centre. We've got work ta do 'n' I ain't hangin' around ta listen ta you two bickerin'."

"Enough said." Leo agreed. "Let's boogie."


	9. Assassino

**Time skip.**

* * *

Louisa slammed the hilt of her sword into the creature's face, hearing a satisfying crunch of bone.

There was a small group of children, roughly fifteen of them, all aged from three to ten. For each child, there was a humanoid, alien fish creature. Louisa had killed three and had left two to bleed to death with paralysing and mortal wounds.

She was fighting ten more on her own. Joy.

Three ran at her, shrieking that ear-damning shriek. Louisa threw her knife at the one in the middle, approving the dull thud as the knife embedded itself in the thing's forehead.

Louisa kicked one away, beheaded the second as the first one charged towards her again. She twisted under its arm and appeared behind it. She slammed her sword back, burying it to the hilt between its shoulders. The tip of her sword protruded from the creature's chest, dripping in gore and green blood.

Five of the remaining creatures stormed towards her, bellowing pig-like squealing battle cries. Louisa braced herself, but the three at the back fell consecutively, each face-planting the ground. She caught a glimpse of a silver knife each in the back of their heads before she was joined by the other two monsters.

Louisa quickly lopped the arms of off one and disembowelled the second. She kicked the second one over and ran her sword through the armless one's head.

By the end of it, she was highly splattered with green blood. Her sword was no longer a golden-bronze colour but a metallic green. She noticed that the two alien fishes who had remained as guards had met their ends with a throwing knife in their eye.

"Fifteen of 'em against you. That's hardly fair." Louisa turned and grinned. Lucy-Jo returned the grin before moving forward and collecting her knives.

Lucy-Jo was the first female Assassin in a global clan called the Keepers. **(Read Percy Jackson meets the First Female Assassin). **She was from England, yet had a similar speaking pattern to Louisa. Lucy-Jo's thick auburn hair was pulled back into a high ponytail and her emerald green eyes studied the group of children. She wore robes that Louisa had never seen on the Assassin before.

The deep blue hooded cloak was roughly tear-shaped with the end at a point just below Lucy-Jo's knees. There was an upside down triangular shawl that covered the Assassin's torso. It was the same colour as and attached to the cloak. Lucy-Jo had the cowl- the hood- down, which Louisa thought was unusual. Assassins were supposed to protect their identity. Lucy-Jo wore black trousers of strong, flexible, warm and durable material with a matching long sleeved shirt. Around her hips was a deep purple belt, a slimmer version of Leo's tool belt. The pouches were of alternating colours- the top of one pouch was black, the bottom of it deep blue. The next pouch was blue on top and black on the bottom and the following pouch was the same as the first. Lucy-Jo's shoes were strong and durable, slim line trainers, the same purple all over as her belt. On her wrists, Lucy-Jo wore deep purple gauntlets that finished at a point on both ends, one point supporting her wrists and covering the back of her hands; the other point neatly tucking into the crook of her elbow. **(For a coloured drawing, PM me to see it on Deviantart). **

"What's with the snazzy get-up?" Louisa asked. Lucy-Jo looked down at herself before grinning at Louisa.

"I am now the first female Master Assassin."

"Nice." Louisa smiled approvingly. Lucy-Jo nodded in agreement, her eyes returning to the grouped children. The youngsters were watching them fearfully.

"What are we gonna do 'bout them?" Lucy-Jo asked.

"We're puttin' the mortal kids in both camps until all this sh- stuff," Louisa had caught herself from swearing with young children present. "Is sorted." She finished.

"Right. How? Or have ya got some demigod magic up ya sleeve?" Louisa smirked.

"I do, actually." Louisa's sword snapped back into watch form. She tugged back her sleeve, revealing a burnt on tattoo of a trident. It had been placed there with the similar method of Camp Jupiter's stripy forearms.

Lucy-Jo looked at her expectantly. Louisa covered the trident with her hand for a few seconds before looking up.

A glowing green trident as tall as Louisa floated in mid-air between the demigod and the Assassin. "Camp Half-Blood!" Louisa demanded. The trident shimmered and stretched in size until it was a circular portal showing the porch of the Big House. "Chiron, more kids!"

"Send them through, Louisa." Louisa turned to the mortal children.

"Ya all gonna go somewhere safe until we can get ya back with ya parents, 'kay?" They all nodded, but kept glancing fearfully at the portal. "Uh… think of it as a teleporter, yeah?" They nodded again, relaxing slightly. Louisa did a quick head count to double-check. "One at time, OK?" She counted the children as they passed through the portal.

Surprising her, the youngest child stopped. Louisa knelt. "What's the matter?" The young girl bit her lip, her blue eyes on Louisa.

"Thank-you." The girl said quietly, hugging Louisa. Louisa was stunned for a second before gently returning the hug. "I tell my friends demigods are good. I tell Mommy and Daddy too when I find them."

"Thank-you." Louisa smiled. "Now go before the thing closes." The girl tightened her arms briefly before pulling away. She gave one last wave before walking through the portal.

The portal closed. Louisa stood up straight, staring at the spot where the girl had disappeared.

"At least someone's grateful, huh?" Lucy-Jo smiled.

"Yeah…" Louisa pulled herself together. "Team-up?" She suggested.

"Ya read my mind." Lucy-Jo grinned. Louisa returned it, but it felt fake.

Of all the people, a three year old girl had shown her gratitude and faith.

_Maybe the world needs some more three year olds_, Louisa thought sadly;_ they can show the grown-ups a thing or two._


	10. Dangerous love

"See?" Leo pointed. He had met up with Louisa, Lucy-Jo and a trio of toddlers two minutes ago. "The whole thing just folded up." They stood on a road bridge, looking down at the scene below. Three roads travelled north. The one on the left eventually veered to the left. The one on the right eventually veered to the right.

The one in the middle used to carry on straight. Now it slowly curved up into the sky like a rollercoaster. At the very top was a huge portal, swirling and glowing greens, blues, purples and white. At the very bottom were a hoard of land and range rovers, all driven by some fish monsters. They knew how to fly great big complicated spaceships but they didn't know how to drive a car of the idle human species past five miles an hour.

Leo looked worried. "None of the cars have gone through yet. At the speed they're going, it'll take between an hour and an hour and a half to get to the top."

"Let the buggers go." Louisa said, turning away. Leo grabbed her by the arm and forced her to turn around again.

"There are kids in those cars!" He protested. Louisa's opinion suddenly changed.

"Right." She touched the mobile phone ear piece all demigods had been given to stay in contact with each other. She issued directions to where they were before explaining the situation. "We all need ta be here 'n' pronto. Any kids ya find along the way, send 'em ta the camps quickly." Louisa signed off.

"What are we going to do?" Leo asked, tugging his sleeve back. All demigods had been burnt with the enchanted tattoos that corresponded to their godly parent. Leo's was a fiery hammer and he was quite proud of it.

He opened a portal and kindly ushered the three toddlers through. The portal closed.

Louisa studied the chaos around the cars. Monsters – humanoid and ones like the one from the swimming pool – were battling armoured demigods and gods- minor and major.

"We help them." She looked at Lucy-Jo. "Are you the only one here or did ya bring the whole party?"

"All of us. Nearly a million from all over the world."

"Tell 'em scratches and bites from those things can cause 'em to turn into the same thing," Lucy-Jo scowled at this, "but we need 'em here ta help. All of them." The Assassin turned away and started relaying the messages. Louisa noticed that her Assassin friend repeated the messages in several different languages.

"Lou?" Louisa looked at Leo. He seemed nervous and sheepish but clearly trying to hide it.

"What's the matter?" Louisa asked, for once, genuinely concerned. Leo struggled with his words before simply holding his arms out in a silent request for a hug.

Louisa was aware of Lucy-Jo talking animatedly in French ten feet away as she stepped into Leo's arms to offer reassurance.

"I'm… I'm scared…" Leo admitted in a small voice.

"We all are, Valdez."

"You don't seem scared though." Leo mumbled into her shoulder. Louisa had to think before answering.

"The kids are more scared. We've gotta be strong just ta give 'em that small bit of hope." Leo nodded. He was silent for a few seconds, mustering the courage to ask her something. Lucy-Jo was arguing very colourfully with someone on her phone. Her back was still facing them and she moved further away, putting a distance of fifteen feet between them.

"Lou, I wanna… I wanna do something in case we end up as alien monsters."

"Valdez, don't think ya _dare_ think like that!" She scolded.

"Sorry for being a realist." He muttered. She sighed.

"What'd ya wanna do?" Leo hesitated, but forced himself to hold her at arm's length. She made to ask him something, but Leo cut her off by leaning forward and grazing his lips over hers.

He had crushed on Louisa for weeks now. It wasn't a silly crush, like his previous ones. He had spent as much time as possible with her for the past month and he had grown increasingly fond of her. Maybe a bit too fond if he wanted to keep his head on, but hey, the world was ending and he had been single all his life. That was no fun. Especially when his friends had girlfriends and continuously tried to set him up with girls he didn't really take a fancying to. It was just torture.

Leo hovered, less than a centimetre from kissing her properly. Neither of them moved. She was too stunned at his courage- or stupidity- and he was too nervous to finish the deed now he had started it.

A warm tingle worked its way down Leo's spine and he found himself relaxing. His shyness slowly faded away and he managed to find the courage to press his lips to hers.

She remained stunned for a few seconds. Leo actually whimpered, pleading her to respond. He was ecstatic and relieved when she did.

The kiss was soft and sweet. It was also highly relaxing for the pair of them.

But it didn't last long.

They had work to do.


End file.
